Engine-powered vehicles, recreational equipment, and machines commonly use battery-powered electric motors to start their engines. Such starter motors have a variety of failure modes. A typical maintenance procedure when starter motor failure is suspected involves removing the motor and testing it using dedicated test equipment. Such a unit of test equipment typically consists of a bracket to which the motor under test can be clamped, a wall-plug-AC-powered DC power supply, heavy-duty cables to feed the power to the motor under test, and a variety of connection and control schemes to allow any of the various styles of starter motors to be actuated in a way similar to their normal on-engine actuation modes.
In pursuit of minimization of complexity and component cost, typical starter motor testers employ simple power supplies and provide no direct indication of the condition of the starter motor, relying on the experience of the operating technician to decide whether the sound of the running starter motor is “about right”. While effective for diagnosing simple failures such as worn-out brushes, shorted commutators, open field windings, and failed hold coils, and to verify that a replacement starter motor acts nominally as part of a sales transaction, such tester designs may fall short when testing newer starters. For example, recent starter motor designs can differ greatly, so that technician experience may be less reliable as a guide to motor condition. Meanwhile, starter motors for fossil/renewable hybrid and low emissions vehicles may be used at virtually every vehicle stop, so demands for starter motor reliability and durability can increase, which can in turn dictate a need for higher analytical precision in a tester. Conventional tester designs may also fail to take advantage of recent innovations in electronic components and concepts that promise significant benefits, including the capability to detect failure modes that may be partially masked when starter motors are run without a load.
Incorporating into a starter motor tester the capability to apply a mechanical load simulating an engine sized for each motor has presented disadvantages. The variety of dimensions of run-away clutches, as well as the variety of mounting bracket styles used to affix starter motors to engines, makes the mechanical connection of a starter to a load simulator a significant challenge. Such a load simulator, in turn, would have significant technical challenges to its implementation in support of all likely engine types, from motorcycles to heavy trucks. Temperature testing to verify a starter motor's ability to function in a worst case would be desirable, but would require chilling the starter motor to simulate extreme winter conditions, which presents the disadvantage of complexity.
Accordingly, there is a need in the art for a starter motor tester that provides increased test capability compared to conventional designs.